Homer Public Works Department is testing wastewater for signs of COVID-19
Knowing how many people in Homer have COVID-19 is crucial to safely opening up business on the peninsula. With narrow parameters for who can be tested and an initial scramble for test kits and protective equipment, local health care providers have only been able to determine so much. KBBI's Kathleen Gustafson has the story on the city of Homer's efforts to detect COVID-19 in wastewater.
South Peninsula Hospital is expanding its list of symptoms and performing an increasing number of tests. As of Thursday morning, April 30, 2020, SPH has submitted 277 tests, nowhere near enough to get a clear picture. Gaging the health of the whole community requires a broader perspective, so the City of Homer has joined a study conducted by Biobot Analytics in Somerville, Massachusetts.
Biobot is collecting and testing wastewater from 160 public works departments in the United States. Homer’s wastewater treatment plant is the only site in Alaska.
Biobot’s first project, when it was founded in 2017, was to test for opiods in wastewater. Now they’ve developed a process and a formula to calculate coronavirus in wastewater.
Todd Cook is the City of Homer’s Wastewater Superintendent. He says he receives a test kit from Biobot every two weeks, collects a sample and sends it back for testing.
“ So we have auto-samplers that start about 8 o’clock in the morning on a Tuesday morning and run for 24 hours and they take about a hundred to 300 mils of sample. And then, we ship them, and then we wait for them to come back with results."
Cook says the samples that the city sends are collected before any sewage treatment takes place. What Homer sends to Biobot is called raw influent. When the samples arrive in Massachusetts, Biobot processes the samples in order to concentrate and inactivate the virus. They extract RNA, a nucleic acid, from the sample. RNA carries genetic information.
Then, Biobot sends the sample to their partner lab at MIT. What they get back is a “number of copies of the genetic fragments of the virus.”
Here’s Biobot President and Cofounder, Newsha Ghaeli
“And then we apply a formula to that raw concentration number to get a prevalence estimate. It’s expressed as a percentage but also, given that we know the population coverage of the wastewater facility, we can also convert it to an estimated number of cases,” said Ghaeli.
Superintendent Cook says participating in the study is minimal extra work for the city. They collect and send samples to Biobot and then get on with the testing and treatment that they perform every day at the wastewater treatment plant at the end of Heath Street in downtown Homer. They separate the solids from the liquid and then treat the liquid waste with an ultraviolet disinfection process, so that bacteria and viruses can’t reproduce.
“They have such a short life cycle. You stop them from reproducing and they die off. We have a limit for what we call fecal coliform - kind of an indicator organism. If you’re killing off your fecal coliform, there is a lot of other pathogenic bacteria that are not as strong, so EPA is assuming that you’re getting kill on those pathogens also,” said Cook.
Back at Biobot, Ghaeli says their goal is to help communities measure the scope of the outbreak in a way that adds to the data produced by hospital testing since sewage testing includes information on asymptomatic patients.
"…who either have no symptoms or very mild symptoms but can still be contagious. This information is very important to have when making decisions like, when do we send our kids back to school and people back to work,” Ghaeli said.
Jenny Carroll, Communications Coordinator for the City of Homer says that the city has a lot to gain from the data in the reports they’ll receive from Biobot.
Carroll said, "It’s being shown in scientific studies that coronavirus can be passed before symptoms show up, potentially. And so, that’s why this wastewater testing helps provide, perhaps, early warnings of disease outbreak.”
So far, The City of Homer has only sent one sample for testing. They plan to continue collecting and sending wastewater to Biobot through the month of May. KBBI will update listeners on the data and assessments that come back to the city.
Image of Todd Cook from Treatment Plant Operator Magazine